Air actuated platen for sanding machines



9 o. w. SMITH 3,049,839

AIR ACTUATED PLATEN FOR SANDING MACHINES Filed Feb. 29, 1960 2 Sheets-Sheet 1 II O I u III /3 l 20 Q P J 1 F1 @D 1 o i 16' 2 INVENTOR.

Okson w 5m TH I M J- w Aug. 21, 1962 o. w. SMITH AIR ACTUATED PLATEN FOR SANDING MACHINES 2 Sheets-Sheet 2 Filed Feb. 29, 1960 HTTORNE United States Patent Ofifice 3,049,839 Patented Aug. 21, 1962 3,049,839 AIR ACTUATED PLATEN FOR SANDING MACHINES Orson W. Smith, Seattle, Wash, assignor to Smithway Machine Company, Inc., Seatfle, Wash, a corporation of Washington Filed Feb. 29, 1960, Ser. No. 11,887 1 Claim. (Cl. 51-141) This invention relates to panel sanding machines. More particularly, it has reference to improvements in contour sanding machines of those types wherein a continuous abrasive belt of the full width of the panel, operates about belt mounting rolls and is positioned thereby to engage in sanding contact with a surface of each panel as successively advanced through the machine; such panels generally having a width of four feet and length of from six to twelve feet.

It is the principal object of this invention to provide an improved form of flexible platen for contour sanding of plywood panels, in combination with, or in conjunction with means for causing it to apply pressure against the sanding belt along its line of sanding contact with advancing panels in an manner whereby to insure that while the entire surface area of each will be caused to be sanded to some extent regardless of depressions, humps or other irregularities, that may exist in or on the surface, it will not conform too closely thereto to the detriment of overall smoothness.

It is a further object of the present invention to provide such a platen, comprising a rigid mounting bar equipped with a flexible facing strip and to provide the rigid bar with pressure means at closely spaced intervals therealong, each for applying a regulated pressure against the flexible facing strip to thereby control the depth or extent of sanding of the panel over its entire surface in accordance with its con-tour.

Further objects and advantages of the present invention reside in the details of construction of parts embodied in the platen; in their combination and functional relationship and in the mode of operation and control of the platen in a sanding machine, as will hereinafter be described.

In accomplishing the above mentioned and other objects of the invention, I have provided the improved details of construction, the preferred forms of which are illustrated in the accompanying drawings, wherein:

FIG. 1 is a cross-sectional view of a panel smoothing machine employing platens embodied by the present invention as used in conjunction with panel sanding belts; and showing the disposition of the platens relative to the sanding belts and the advancing panels.

FIG. 2 is an enlarged underside view of a platen and the belt mounting rollers which carry the sanding belt across the platen.

FIG. 3 is a vertical section, taken lengthwise of the platen, as on section line 3-3 in FIGS. 2 and 4.

FIG. 4 is a cross-section of the platen taken on line 4-4 in FIG. 3.

FIG. 5 is an end view of the platen as supported at that end by the belt carrying frame.

FIG. 6 is a view showing the platen in cross-section and in isometric view.

In the following specification, the term sanding belt will apply to any abrasive or smoothing belt, similar to or equivalent to that shown, which is adapted for a surface smoothing operation in accordance with disclosures in my prior application filed under Serial Number 250 on January 4, 1960.

Referring more in detail to the drawings:

In FIG. 1, platens of the present invention have been shown as used in a present day plywood panel sanding machine. This particular machine is shown to comprise identical upper and lower sanding units whereby the top and lower surfaces of plywood panels may be simultaneously sanded in the advancing of the panels horizontally between the units.

In this view of the drawings, the sanding units, designated in their entireties by reference characters, U and U, respectively, comprises a continuous sanding belt 10 operable about two mounting rolls, 11, 12 and a platen 13; these latter parts being in parallel relationship and supported at their ends by adjustable frame structures 14-44 in such manner as to support the endless belt 10 for travel along a triangular path and, in its passage, to pass across the outer face of platen 13 and to be pressed thereby into sanding contact with the adjacent surface of each of the panels as they are successively advanced through the machine.

In FIG. 1, plywood panels, designated by reference character P, are shown as being advanced for sanding by and between a plurality of paired sets of feed rollers 1515, which may be driven by any suitable means, not herein shown, and it is further to be understood that one or both of the belt mounting rollers 11 and 12 of each unit may be driven to effect operation of the sanding belts 10; the direction of travel of the sanding belts and panels P being herein designated by the arrows placed adjacent thereto in FIG. 1. It is farther to be observed in the present instance, that the sanding belts 10 travel in directions opposite to that of the panels at their lines of contact with the panel surfaces.

In the following portion of this specification, only the platen of the upper sanding unit U will be described, with the understanding that the description of it applies equally to the lower unit U.

Referring now more particularly to FIGS. 2 to 5 of the drawings, it will be observed that the platen, designated in its entirety by numeral 13, is mounted between and parallel with paired rollers 20-20 that are placed in rather close relationship to the platen; the two rollers and the platen being mounted at their opposite ends by suitable bearing blocks 212I which are bolted or otherwise fixed to the opposite end frames 14 and 14 shown in FIG. 3, which support the rolls and belts. These paired rollers 20-49 coact with and operate to carry the sanding belt 10 across the platen 13 which is equipped with means for pressing the sanding belt 10 against the panels for their sanding, as will presently be described.

For better understanding of the purpose of the present invention, it will here be mentioned that the surfaces of plywood panels that are to be sanded are not always perfectly fiat but may be found upon close inspection to have humps, valleys, depressions and various other surface irregularities that cannot be detected by ordinary eyesight and it has been the principal object of this invention to provide a platen that will cause all the ordinary surface irregularities to be sanded and all high spots brought to a more uniform plane or flat surface.

To accomplish the above objects, I utilize a platen 13 that comprises a substantial, rigid and relatively heavy base bar 1311 to which a relatively thin facing strip 13x of coextensive length is fixed, as will be best understood by reference to FIGS. 3 and 4. This facing strip 13x is quite flexible and extends along the base bar 13b, being fixedly mounted on the lower ends of pistons 24 that extend from cylinders 25 that are formed in close, parallel relationship along the base bar or cylinder bar 13b, as extended between the platen mounting blocks. It will further be observed, by reference to FIG. 3, that all pistons 24 extend to the same extent from the lower face of the cylinder bar 13b and each piston is equipped at its outer end with a round head portion 24h that is fitted in a slot 29 of dove-tailed formation that extends within and along the inside surface of the flexible facing strip 13x.

Each cylinder 25 is open at its upper end to an air channel 32 that extends lengthwise of the inner face of a bar 13t overlying the bar 13b. This channel has a connection, as at 34 in FIG. 3, with a supply line 35 through which air under controlled pressure controlled by a regulator 35x is admitted to serve all cylinders.

All pistons 24 are of the same diameter and subjected to the same amount of air pressure, thus to cause them to exert equal downward pressure against the flexible strip 13x. It is also shown in FIG. 3 that each piston is equipped with suitable packing rings 38 and has its lower pontion reduced in diameter to receive a coiled spring 40 thereabout; these springs all being retained under a predetermined compression by a cover plate 41 that extends along and is fixed to the base bar 13b over the lower ends of the cylinders 25 and which plate has openings 42 therein through which the reduced outer end portions 41 of the pistons extend.

In the use of the present platen 13, as comprised by the base bar 13b and facing strip 13x, it is functionally mounted between the paired rollers 20-26 as shown in FIG. 4; the flexible platen strip 13x being so disposed as to hold that part of the sanding belt 16 that crosses it, in sanding contact with the adjacent surface of an advancing panel P. Air under pressure is admitted under valve control to the channel 32 of the base bar 13b and from it is applied equally to all cylinders to urge the pistons downwardly; the function of these pistons being to press the flexible strip 13x against the sanding belt to cause it to quite closely conform to the general contour of the panel surface, to enter all depressions to some extent and to sand off all high spots. This results in a completely sanded panel surface; a reduction or removal of high spots giving the panel a more even contour; greater smoothness; a better appearance for finishing and a finished panel of increased value.

The present invention has been illustrated in connection with a sanding machine of the same type as that of the machine shown in US. application filed under Serial 250. However, it may readily be adapted for use with various other types of machines and for the smoothing of panels other than those of plywood. It can also be used in stroke sanders where the platen might be quite elongated and the belt running in its lengthwise direction.

What I claim as new is:

A panel sanding machine including means for supporting and advancing a panel therethrough for the sanding of a surface thereof, said machine including a driven sanding belt operable for the sanding of a surface of the panel incident to its movement through the machine, a platen supported in the machine for pressing said sanding belt against the panel surface to effect the sanding thereof as the panel advances, said platen comprising a rigid relatively heavy elongated base portion extending transversely to the direction of movement of a panel through the machine and including a relatively thin quite flexible elongated continuous facing strip in contact with said sanding belt durin g operation, said heavy base portion having a plurality of cylinder chambers formed therein and spaced along the length thereof, a piston slidably disposed within each of said cylinder chambers, one end of each of said pistons being secured to said facing strip at spaced portions along the length thereof, resilient means normally urging said pistons in a direction so as to move said pistons away from a panel passing through the machine, fluid pressure means disposed in communication with each of said cylinder chambers for introducing fluid pressure against the opposite ends of each of said pistons for urging said pistons toward a panel passing through the machine, each of said pistons being of the same size and being subjected to the same amount of fluid pressure during operation such that equal pressure is applied by each of the pistons against the associated portions of the flexible facing strip, whereby the facing strip will cause the sanding belt to quite closely conform to the general contour of the panel surface, to enter all depressions in the panel surface to some extent and to sand off all high spots on the panel surface.

References Cited in the file of this patent UNITED STATES PATENTS 1,927,330 Williams Sept. 19, 1933 2,618,913 Plancon et al Nov. 25, 1952 2,761,256 OConnor Sept. 4, 1956 

